The present invention relates to a semiconductor integrated circuit device; and, more specifically, the invention relates to a technique which is applicable to a voltage step-down power supply circuit, for example, of the type used in a one-chip microcomputer.
The following documents have been reported as disclosing examples of a semiconductor integrated circuit device including an internal voltage step-down power supply circuit. The Japanese Published Unexamined Patent Application No. 117650/2001 (hereinafter referred to as the document 1) indicates that power consumption in the standby operation can be lowered by using a first internal voltage step-down circuit for an active operation, which exhibits a large current consumption, but assures an excellent response characteristic, and a second internal voltage step-down circuit for a standby operation, which has inferior response characteristic, but exhibits a small current consumption through the switching operation. The document, “A tunable CMOS-DRAM Voltage Limiter with Stabilized Feedback Amplifier”, IEEE J. SOLID-STATE CIRCUITS, Vol. 25, No. 5, October 1990 (hereinafter referred to as the document 2) describes voltage trimming through switching of the serial/parallel conditions of a MOSFET.
[Document 1]
Japanese Published Unexamined Patent Application No. 117650/2001
[Document 2]
“A tunable CMOS-DRAM Voltage Limiter with Stabilized Feedback Amplifier”, JEEE J. SOLID-STATE CIRCUIT, Vol. 25, No. 5, October 1990